Brilliant thread Alex, thank you!
I'm wondering if you could do a follow-up on your last post dealing with resolution, and explain how to do basic star testing of optics? I'm doing this a lot with my new scope, but I'm not sure what all the different rings represent, and whether they can be used to determine '
x-number of waves de-focus...
It could well be explained elsewhere, but you have a great way of presenting the information clearly...
Cheers
Stephen